Particle‐Specific Toxicity of Copper Nanoparticles to Soybean (Glycine max L.): Effects of Nanoparticle Concentration and Natural Organic Matter

Abstract

For the soluble metallic nanoparticles (NPs), which forms (particles [NP (particle) ] vs. dissolved ions [NP (ion) ]) are the main cause of toxicity of the NP suspension (NP (total) ) remains uncertain. In the present study, soybean was exposed to Cu NPs in a hydroponic system to determine how natural organic matter (NOM; 10 mg/l) and concentration of Cu NP (total) (2-50 mg/l) affect the relative contributions of Cu NP (particle) and Cu NP (ion) to the overall toxicity. We found that NOM mitigated the phytotoxicity of Cu NP (particle) more significantly than that of Cu salt. When no NOM was added, Cu NP (particle) rather than Cu NP (ion) was the main contributor to the observed toxicity regardless of the concentration of Cu NP (total) . However, NOM tended to reduce the relative contribution of Cu NP (particle) to the toxicity of Cu NP (total) . Especially at a low concentration of Cu NP (total) (2 mg/l), the toxicity of Cu NP (total) mainly resulted from Cu NP (ion) in the presence of NOM (accounting for ≥70% of the overall toxicity). This might be attributable to the combined effects of increased dissolution of Cu NPs and steric-electrostatic hindrance between Cu NP (particle) and the soybean roots caused by NOM. Fulvic acids (FAs) tended to reduce the role of Cu NP (particle) in the overall toxicity more effectively than humic acids (HAs), which might partially be due to the higher extent of Cu NP dissolution on FA treatment than in HA treatment. Our results suggest that because of the relatively low metallic NP concentration and the presence of NOM in natural water, NP (ion) are likely problematic, which can inform management and mitigation actions.

Trophic transfer of Cu nanoparticles in a simulated aquatic food chain

“…A relatively high uptake of Cu and altered nutrient quality in soybean (Glycine max) grown in agricultural soil amended with CuNPs (Xiao et al, 2022) were reported. Moreover, natural organic matter increased the dissolution of CuNPs, and mitigated the phytotoxicity of CuNPs more significantly than that of Cu salt (Xiao et al, 2021). The increasing use of Cu-based NPs in agricultural, industrial and environmental applications will undoubtedly lead to their spread in terrestrial ecosystems (Bakshi and Kumar, 2021).…”

Bacillus altitudinis‐Stabilized Multifarious Copper Nanoparticles Prevent Bacterial Fruit Blotch in Watermelon (Citrullus lanatus L.): Direct Pathogen Inhibition, In Planta Particles Accumulation, and Host Stomatal Immunity Modulation

“…[ 13 ] Similarly, chemical‐based CuNPs at 500 mg kg −1 soil significantly reduced the incidence of tomato bacterial wilt by ≈37% through inhibiting the growth and biomass of the pathogen Ralstonia solanacearum . [ 14 ] Earlier studies frequently reported phytotoxic effects of Cu‐based nano‐ or bulk‐agrochemicals on the morpho‐physiological traits of different plant species; for example, Cucurbita pepo , [ 15 ] Coriandrum sativum , [ 16 ] Glycine max , [ 17 ] Mentha spicata , [ 18 ] and Cucumis sativus . [ 19 ] However, bio‐NPs have inherently reduced toxicity and greater biocompatibility, often outperforming their chemically synthesized counterparts.…”